Insulators are commonly employed for supporting high voltage electrical components and maintaining those components in a spaced relationship relative to other structures as well as the ground. Often such insulators are subjected to tensile stresses. For example, the insulator can be used as a hanger for supporting a transmission line with the insulator being suspended in tension between an arm of a tower and the transmission line. The insulator has a pair of end fittings for supporting and coupling the insulator to the support arm of the tower and to the transmission line.
As the voltage of the power transmission line increases, the length of the insulator supporting the transmission line must also be increased. Accordingly, insulators used with high voltage lines can be very long and heavy. This results in the end fittings being subjected to a large tensile stress or force, which requires the end fittings to be constructed as large, heavy duty members.
One example of an insulator is disclosed in U.S. Pat. No. 3,898,372 to Kalb. This insulator includes a central rod of insulating material, such as fiberglass. The ends of the rod include end fittings or coupling members for attaching the rod to transmission lines and to supporting structures. The central rod is surrounded by a series of weathersheds of a rubber-like polymeric material, for example, EPM. The weathersheds are placed end to end along the rod to form a long external surface path. A dielectric material fills spaces between the weathersheds and the insulator central rod to fill any voids between the rod and the weathersheds and to exclude contaminants and moisture which might otherwise form a conductive path.
Another example of an insulator is disclosed in U.S. Pat. No. 4,610,033 to Fox. This insulator has a pair of end fittings or coupling members for coupling the insulator between a support arm of a tower and a transmission line by a pair of shackles. The end fittings of this insulator are constructed of a metallic material.
Other examples of prior insulators with metallic end fittings are disclosed in U.S. Pat. No. 4,303,799 to Ishihara et al and U.S. Pat. No. 4,343,966 to Pargamin. The end fittings of these insulators have circular openings for coupling the insulators to supporting members.
In view of the above, it is apparent that a need exists for an insulator having end fittings or coupling members which reduce the stress within the end fittings to permit the end fittings to withstand higher tensile loads. This invention addresses this need in the art along with other needs which will become apparent to those skilled in the art once given this disclosure.